MOSCOW
(Sputnik) — The militants of Daesh militant group used poisonous
gas in an attack against a Syrian army airbase in the province of
Deir Ez-zor, a military source said Tuesday.

"The
Daesh [Daesh] militants attacked the military airfield in Deir Ez-zor
with shells containing a poisonous chemical substance. The defenders
of the airbase have reported that a number of soldiers were choking,"
the source told RIA Novosti.

Syria
has been in a state of civil war since 2011, with the army loyal to
President Bashar Assad fighting several opposition factions and
militant groups, including Islamic State (IS, also known as Daesh,
banned in a range of countries including Russia).

In
August 2013, an unprecedented chemical weapons attack which killed
more than 1,300 civilians took place in Ghouta, a suburb of the
Syrian capital Damascus. Militants and Assad’s government blamed
each other for the attack.

A
mission to eliminate Syria's chemical arsenal was announced after the
deadly gas attack. Moscow urged Damascus to place its chemical
weapons under international control, and Syria agreed to the Russian
initiative.

In
August 2015, the UN Security Council authorized the launch of a Joint
Investigative Mechanism (JIM) to identify people who were involved in
the use of chemical weapons in Syria.